The invention relates to a method for the pictorial representation of a three-dimensional measured data record. The invention in particular relates to a device and a method for virtual endoscopy, such as in particular virtual coloscopy.
The pictorial representation of three-dimensional measured data is a general important task of computer-assisted data analysis and preparation. Imaging methods are increasingly important, in particular in the medical field. In this field, X-ray photography, radiograms, nuclear spin tomography pictures etc. can be evaluated for diagnostic purposes.
One example of use relates to the endoscopy of the large intestine (colon), the so-called coloscopy, which is conventionally performed by means of an endoscope especially developed for this purpose. Such a coloscope comprises an optical system which is, as a rule, connected to a screen to permit the physician to make a diagnosis. The introduction of the coloscope into the intestinal area is perceived as unpleasant or even painful by many patients, and there always is a risk, in particular in case of inflammations of the intestinal wall, that the intestinal wall is pierced by the coloscope.
Virtual coloscopy has therefore been developed as an alternative, where no physical coloscope has to be introduced into the body of the patient. The methods and devices of computer tomography/nuclear spin tomography are rather employed instead of coloscopes for recording measured data and optically representing these data. The development of virtual coloscopy has been decisively supported by the fact that the performance of complex image processing methods has meanwhile become possible without difficulties thanks to the high computing power of recent computers.
For virtual coloscopy, a high number of parallel sections is recorded spatially resolved with a tomography means. One set of two-dimensional image data corresponds to each of these sections. These sets are converted into a three-dimensional measured data record with the assistance of a computer. From the three-dimensional measured data record, two-dimensional image data can in turn be calculated, which are independent of the orientation of the section during the actual measurement, e.g. oblique with respect to it. The two- and three-dimensional image data are as a rule reproduced on two-dimensional reproduction means (monitor, photography, etc.) as tomograms (i.e. all imaged matrix dots emanate from one intersecting plane), or as quasi three-dimensional images which impart a spatial impression in a manner similar to that of a conventional photography (the imaged matrix dots do not all emanate from one and the same plane).
It should be noted in this context that a priori no determinations can be made as to which of the views is best suited for a diagnosis as significant as possible. Although the spatial (quasi three-dimensional) representations are very demonstrative due to the imparted spatial impression and are thereby of assistance for the orientation, just in these representations, diagnostic findings, such as lesions etc., can be hidden by tissue (e.g. a fold in the intestine) and therefore not be visible. In contrast, in tomograms there are no such hidden sites, however, in the performance of a treatment that normally necessitates a coordination into three directions in space they are not very helpful.
The German patent application DE 10246355 A1 discloses a method and a device for the simultaneous pictorial representation of measured data that have been taken of a large intestine in several, two- and three-dimensional views. In one of the views, a selection can be made the relative position of which is shown in the other views. The automatic orientation of the individual pictorial representations with respect to one another, however, is fixed, which makes a quick, easily manageable and arbitrary change of the viewing direction, in particular the relative position of the intersecting planes of one of the representations to another one, impossible. This, however, is extremely desirable for diagnostic reasons and with respect to the acceptance of such a device by the market.